Vernadsky, George 1887-1973.
A history of Russia /
George Vernadsky, Michael Karpovich 
. - New Haven : Yale University Press,  1943- 
. - v.  24 cm. 
<br/> V. 1. Ancient Russia  <br/>  V. 2. Kievan Russia  <br/>  V. 3. The Mongols and Russia <br/>